This invention relates to restriction enzymes from Bifidobacteria and the method for manufacturing the enzymes.
Restriction enzymes are endonucleases which recognize specific nucleotide sequences on double-stranded deoxyribonucleic acid (DNA) and cleave it at or near the sequences, yielding unique fragments of DNA.
Since the discovery of a restriction enzyme in Haemophilus influenzae, a number of restriction enzymes have been isolated from a broad range of bacteria (Roberts, 1980).
Due to their unique property of dissecting DNA at specific sites, these enzymes have found usefullness in a wide variety of applications in DNA research, including physical mapping of genes, DNA sequence analyses, gene isolation, and recombinant DNA technique.
While many restriction enzymes of different specificity are known, it is still required to have novel specificities for further characterization of DNA molecules and for the construction of recombinant DNA molecules in vitro, and to have better sources of some of the known enzymes for practical purposes.
We have examined many species of nonpathogenic, intestinal bacteria for the presence of restriction enzymes, and found that Bifidobacteria produce a variety of these enzymes with properties advantageous to practical use.
Bifidobacteria are easy to grow on a large scale, and the enzymes can be purified in a straightforward manner because of their remarkable stability and the low level of interfering nuclease activities in the crude extracts.
Among Bifidobacteria screened for restriction enzymes, 8 in 15 strains from 9 species showed enzyme activities. These strains are listed below.
B. bifidum YIT4007: FERM-P 5871 PA0 B. breve YIT4006: FERM-P 3906 PA0 B. infantis 659: ATCC25962 PA0 B. infantis S76e: ATCC15702 PA0 B. longum E194b: ATCC15707 PA0 B. thermophilum RU 326: ATCC25866 PA0 B. breve S1: ATCC15700 PA0 B. breve S50: ATCC15698